1. Field of the Invention
This invention relates generally to a system for reducing vehicle roll and, more particularly, to a system for reducing vehicle roll by controlling the friction-force of a damper at one or more of the wheels of the vehicle.
2. Discussion of the Related Art
Various vehicle control systems are known in the art that improve driver convenience, safety and comfort. One of the areas of control for vehicle control systems is the roll motion of the vehicle.
The centrifugal force on the body of a vehicle induces a vehicle roll during cornering. This vehicle roll may cause driver and passenger discomfort, vehicle instability and possibly even vehicle rollover. To prevent these adverse effects, vehicle roll may be reduced using an active or semi-active roll control system. However, known active vehicle roll control systems typically require a hydraulic system that increases system complexity and cost. A passive anti-roll bar can be used to reduce vehicle roll without a complex hydraulic system, but such an anti-roll bar tends to increase the suspension harshness by transmitting road disturbances, such as from a single wheel pothole or bump.
An attempt to overcome some of the drawbacks discussed above is provided by U.S. Patent Publication No. 2005/0253350, titled Roll Control System, Device and Method for Controlling Vehicle Stability. The system disclosed in this publication uses magnetorheological actuators to engage anti-roll bars to control the roll motion of the vehicle only when needed. However, this system still requires additional actuators to control the anti-roll bars, which also acts to increase system complexity and cost.